John S. Kiernan

Mediator/Arbitrator/Independent Panelist

(949) 760-5288

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To book a mediation with John S. Kiernan, please call ADR Case Manager Meghan Lettington at (949) 760-5288 or write to her using the form below.

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John S. Kiernan became of counsel at Debevoise & Plimpton LLP on January 1, 2022, after more than 40 years at the firm.

He served on the firm’s Management Committee, as Co-Chair of its Litigation Department for twelve years, and as Chair of its Ethics Committee for twenty-seven years. His client representations embraced a broad range of commercial litigations, arbitrations, mediations and internal investigations, including disputes relating to contracts, purchases and sales of businesses, corporate governance, derivative and class action claims, international treaties, securities claims, patents and other intellectual property, consumer fraud, accountant liability and mass torts.

Numerous publications have recognized John as a leading disputes lawyer. Chambers USA has described him as “an extraordinary commercial litigator” whose “instincts and analysis are always spot-on” (2021). Clients have praised his “great judgment” (2010) and recognized him as “technically excellent” (2009), “incredibly creative,” “great when put in front of a board of directors” (2012) and a “superb litigator” (2011). Peers have described him as “an extremely bright, first-class litigator, thinker and colleague” (2008) and a “superstar” who applies a “deft touch rather than a sledgehammer” in commercially sensitive matters (2007). Clients have also said he is “very balanced, and has real gravitas. He’s as cool as can be in incredibly intense situations” (2020). In addition, IFLR Benchmark Litigation Guide has ranked John among the leading commercial litigators in the United States and in New York each year since 2010 and noted “his extensive experience and breadth of knowledge.” The Legal 500 US (2017) has recognized him as a leading securities litigator, and numerous other “Best Lawyers” publications have identified him as a leading litigator for commercial matters or alternative methods of dispute resolution.

John is the Board Chair of Prisoners’ Legal Services of New York and Co-Chair of the Inner City Scholarship Fund, Lawyers Division. He has also chaired the Boards of the International Institute for Conflict Prevention & Resolution (CPR), Legal Services-New York City, the Lawyers’ Committee for Civil Rights Under Law, Volunteers of Legal Service, the Justice Resource Center and the New York City Bankruptcy Assistance Project (which he co-founded). He has additionally served as a director or trustee of the City Bar Justice Center, New York Alliance for the Public Schools, Practicing Attorneys for Law Students, United Way of Pelham, NY, the Pelham Art Center, the Federal Bar Council, the Village Board of Pelham Manor, the International Senior Lawyers Project and the Point O’Woods, NY Association. He served for 15 years as a volunteer coordinator for the AmeriCares/HomeFront home rehabilitation project, and for 28 seasons as a travel soccer coach.

John’s public contributions have included service as President of the New York City Bar Association, Village Trustee and Mayor of Pelham Manor, New York, Chair of the New York Chief Judge’s ADR Advisory Committee, Co-Chair of the Chief Judge’s Task Force on Hurricane Disaster Relief, and member of the NYS Permanent Commission on Access to Justice, the NYS Commercial Division Advisory Council, the Chief Judge’s Committee on Non-Lawyers and the Justice Gap, and the Legal Services Corporation‘s Leadership Council and Disaster Task Force.

John has spoken at numerous seminars and written numerous articles on substantive issues in litigation, approaches to resolving complex disputes and discovery. He is the co-editor of The Litigation Manual (ABA, 3rd ed., 1999) and a contributing author of the “Contracts” chapter of New York Business Litigation (ALM 2014) and the “Mediation” chapter of Commercial Litigation in New York State Courts (Thomson Reuters, 4th ed., 2015). He has also served as an Adjunct Professor at New York University Law School.

John received his B.A. in 1976 magna cum laude from Harvard and his J.D. in 1980 magna cum laude from Harvard Law School, where he was an editor of the Harvard Law Review. From 1980–81, he served as a law clerk to Hon. Walter R. Mansfield, U.S. Court of Appeals for the Second Circuit.

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